The accumulation of biological growth on boat hulls, ship bottoms, ocean rigs, fish nets and other objects immersed in or at the level of sea water is a well-known problem. Biological growth that accumulates on the surface of these objects includes, for example, barnacles, mollusks, annelids, hydroids, algae, diatoms, hydrides, bryozoans, and protozoans. The accumulation of this growth leads to problems such as lowered running speeds due to increase in weight and stream resistance in the case of boats and ships, and a significantly shortened useful life in the case of fish nets, ocean rigs and other structures. In addition to the increase in the cost of fuel for boats and ships, there is also a loss associated in terms of both time and money in the application of remedial measures to the surfaces in contact with water.
One of the most common methods for preventing the accumulation of biological growth on substrates is by the use of anti-fouling paints. Such paints are applied to all surfaces of the substrate that will be exposed to water. Unfortunately, most anti-fouling paints do not prevent fouling for extended periods of time. In addition, many of the compositions used in anti-fouling paints are becoming environmentally unacceptable. For example, copper salts are used in many anti-fouling paints, as is tributyltin. Tributyltin, however, has been the subject of recent environmental restrictions; the use of large amounts of copper is raising environmental concerns as well.
Anti-fouling compositions that result in reduced release of copper to the environment are therefore desired.